Characterization of Multi-Porosity Unconventional Reservoirs and their Relationship to Oil and Gas Productivity

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1 Characterization of Multi-Porosity Unconventional Reservoirs and their Relationship to Oil and Gas Productivity Roberto Aguilera, CNOOC Nexen Chair on Tight Oil and Unconventional Gas Schulich School of Engineering, University of Calgary March 10, 2015

2 Slide 2 OBJECTIVES Discuss multi-porosity unconventional reservoirs. Show that there is a continuum that goes from conventional to tight gas to shale gas to tight oil to shale oil reservoirs Relate pore throat apertures to oil and gas rates in vertical and horizontal wells. Make the work tractable by using actual published data. Multi-Porosity Unconventional Reservoirs 2

3 GFREE A multidisciplinary integration of: Geoscience (G) Formation evaluation (F) Reservoir drilling, completion and stimulation (R) Reservoir engineering (RE) Economics and externalities (EE) Focus is on increasing production rates and ultimate recoveries economically and responsably from tight oil and unconventional gas reservoirs 3

4 OUTLINE Dual-porosity Triple-porosity Multi-porosity in shales Effect on water saturation Flow units: from conventional, to tight gas, to shale gas, to tight oil, to shale oil, to condensate reservoirs Link of petrophysics with decline analysis Conclusions 4

5 (A) Frontier Formation, (B) William Fork, (c) Travis peak, (D) Travis Peak : Shanley et al.,

$0%, Kmax=24mD 3 slot microfracture cross-cutting clasts and sandy matrix 2 1 Intg.$

6 Cadomin Fm. - Elmworth Deep Basin ( W6) 2660.m Ø=5.0%, Kmax=24mD 3 slot microfracture cross-cutting clasts and sandy matrix 2 1 Intg. Ø Flourescence (Moslow, 2005) 6

7 Porosity in Organic Matter (Barnett Shale) (Ruppel and Loucks, 2008) 7

8 COLORADO SHALE (CANADA) Porosity in Organic Matter SEM Imaging, thin section Colorado Shale (courtesy D. Rokosh, ERCB, SPE ) 8

9 DUAL POROSITY Matrix and Fractures (or Matrix and Slot Porosity) 9

10 BORAI S DATA (SPE FE, 1987) Area= 10,000 Km 2, 5 Formations in 14 Abu Dhabi Fields 10

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12 Porosity Exponent m, Mesa Verde Formation, USA (Data Source: Byrnes et al., Kansas Geological Survey, 2006) Fit Using Dual Porosity Model (Matrix and Slots) 2.1 Archie cementation exponent m Core Data phi2=0.002, mb=1.75 phi2=0.001, mb=1.86 phi2=0.0007, mb= Routine Porosity 12

13 POSTDAM (CAMBRIAN), QUEBEC, m b =1.77, m f = 1.2, φ 2 = 0.65% 2.0 DUAL-POROSITY EXPONENT, m 1.5 Core Data Dual-phi Model TOTAL POROSITY SPE

14 Dual Porosity Model (Matrix and Fractures), m f = 1.0 or >1.0 Source: Aguilera, SPE , 2008 m = porosity exponent of composite system of matrix and fractures m b = porosity exponent of the matrix Ø = total porosity, fraction Ø b = matrix porosity of unfractured plug, fraction Ø 2 = fracture porosity = v Ø, fraction v = partitioning coefficient m = log {( vφ) m f + [1 1 ( vφ) logφ m f ]/ φ' m b b } φ' b φ φ = 1 φ f = m f ( m f f 2 f 2 lnφ 1) lnφ Last equation valid for φ 2 greater than zero 2 14

15 CHART FOR EVALUATING NATURALLY FRACTURED RESERVOIRS (mb=2.2) DUAL POROSITY EXPONENT, m TOTAL POROSITY, φ v=0.058 v=0.10 v=0.20 v=0.30 v=0.40 v=0.50 v=0.70 v=0.90 mf = MATRIX POROSITY, φ b (Aguilera, 2003) 15

16 SILICICLASTICS TRIPLE POROSITY Matrix, Fractures and Non-Effective Porosity 16

17 Schematic of Triple Porosity Model (Source: Al Ghamdi et al., SPE , 2010) Non touching vugs (or non-effective porosity) Fractures Matrix 17

18 Tight Gas Sand Petrography courtesy of ConocoPhillips 18

19 Triple Porosity Model (nomenclature as in previous equations) Al Ghamdi et al, SPE m = porosity exponent of triple porosity system m b = porosity exponent of the matrix Ø = total porosity, fraction Ø b = matrix porosity of unfractured plug, fraction Ø nc = non-connected (or isolated) porosity = vnc Ø, fraction vnc = vug porosity ratio m = log φnc + 2 (1 φnc ) + (1 v ) / φ φ φ log φ 2 m b b 19

20 m TRIPLE POROSITY MODEL, mb =

21 Shales: Multiple Porosity Rocks (1) adsorbed gas into the kerogen material (2) free gas trapped in nonorganic inter-particle (matrix) porosity (3) free gas trapped in microfracture porosity (4) free gas stored in fractures created during stimulation of the shale reservoir (5) free gas trapped in a pore network developed within the organic matter or kerogen 21

22 Porosities in Shales SPE , 2014 m = porosity exponent (multiple porosities) m b = porosity exponent of the matrix Ø = total porosity, fraction Ø b = matrix porosity scaled to bulk volume of the matrix, fraction V tker = total volume of kerogen = Ø org +Ø ads +V diff, fraction m = log V t ker + φ 2 logφ (1 V 2 t ker + (1 φ V ) 2 t ker ) / φ b m b 22

23 Modified Pickett crossplot including variable values of m calculated with multiple porosity model (SPE ) Slide 23 Passey Zone 1: φ = 5%, φm = 3.9%, φ2= 0.63%, φorg = 0.9%, φads = 0.2% 23

24 Slide 24 MATERIAL BALANCE APPLICATION (Lopez and Aguilera, SPE , 2013) Contribution of free gas, adsorbed gas and diffusion gas from kerogen to total cumulative gas production in Devonian shale gas reservoirs (Appalachian Basin) 24

25 FLOW UNITS: FROM CONVENTIONAL TO TIGHT GAS TO SHALE GAS TO TIGHT OIL TO SHALE OIL RESERVOIR (THERE IS A CONTINUUM) 25

26 Slide 26 FLOW UNIT A flow unit is defined as a stratigraphically continuous reservoir subdivision characterized by a similar pore type (Hartmann and Beaumont, 1999), for example by a similar rp35 (Aguilera, 2002): rp35=2.665 (k/100φ)^0.45 Multi-Porosity Unconventional Reservoirs 26

27 Conventional vs. Continuous Type Accumulations (Used mostly to Explain Tight Gas) (Pollastro and Schenk; 2002, Moslow, 2008) Slide 27 Multi-Porosity Unconventional Reservoirs 27

28 Slide 28 Real Data Conventional and Low Permeability Rocks Multi-Porosity Unconventional Reservoirs 28

29 Slide 29 Elk City Oil Field (Sneider et al., 1983) One-Column Format Multi-Porosity Unconventional Reservoirs 29

Slide 30 Unconventional Reservoirs, Elk City Oil Field (SPE 165350, 2013) Data

30 Slide 30 Unconventional Reservoirs, Elk City Oil Field (SPE , 2013) Data from Sneider et al., 1983 One-Column Format Multi-Porosity Unconventional Reservoirs 30

31 Unconventional Reservoirs (Elk City Oil Field) Slide 31 Sneider et al, 1983 Multi-Porosity Multi-Porosity Unconventional Reservoirs 31

32 Slide 32 Unconventional Reservoirs, Cardium SS, Pembina Oil Field (Source of Data: MacKenzie, 1975) Multi-Porosity Unconventional Reservoirs 32

33 Slide 33 Real Data Shale Gas Multi-Porosity Unconventional Reservoirs 33

34 Flow Units 34

35 Slide 35 Unconventional Reservoirs: Shale Gas (SPE ) Multi-Porosity Unconventional Reservoirs 35

36 Slide 36 Real Data Shale Gas and Tight Gas Multi-Porosity Unconventional Reservoirs 36

37 Slide 37 Unconventional Reservoirs: Shale Gas and Tight Gas (SPE ) One-Column Format Multi-Porosity Unconventional Reservoirs 37

38 Flow Units GFREE RESEARCH PROJECT 38

39 Slide 39 Real Data Tight Oil Multi-Porosity Unconventional Reservoirs 39

40 Slide 40 Unconventional Reservoirs: Bakken Tight Oil One-Column Format Multi-Porosity Unconventional Reservoirs 40

41 Unconventional Reservoirs, Cardium SS, Pembina Oil Field (Source of Data: MacKenzie, 1975; Hamm and Struyk, 2011) Slide 41 Multi-Porosity Unconventional Reservoirs 41

42 Slide 42 Unconventional Reservoirs: Tight and Shale One-Column Format Multi-Porosity Unconventional Reservoirs 42

43 Flow Units PERMEABILITY (MD) 1.0E E E E E E E E E E E E-10 BC CANADA UTICA B.FW UTICA B.M1H HURON CRUSHED SAMPLES? F HR, B MARCELLUS NIKANASSIN SOFT SHALES B.DEL rp35 microns E E POROSITY GFREE RESEARCH PROJECT 43

44 Slide 44 Theoretical Data Pore Scale Modeling Multi-Porosity Unconventional Reservoirs 44

45 Flow Units (Pore Scale Modeling) Rahmanian et al., SPE Microsimulation at the pore throat level: Pore throat radii Permeability Porosity Relative perms Cap pressures Electrical properties Rock Mechanics Stimulation Prod allocation in commingled completions Viscous Flow Knudsen Number Diffusion Dominated Flow GFREE RESEARCH PROJECT 45

46 Unconventional Reservoirs and Potential Microsimulation at the pore throat level will supplement results of rp, k, phi, rel perms, cap pressures, electrical properties, rock mechanics Brittle? Ductile? Type of Stimulation? Effect of Sw, mud Filtrate, leak-off on embedment? Oil and Gas Rates Multi-Porosity Unconventional Reservoirs 46

47 Unconventional Reservoirs and Potential Microsimulation at the pore throat level will supplement results of rp, k, phi, rel perms, cap pressures, electrical properties, rock mechanics Brittle Ductile Type of Stimulation Effect of Sw, mud Filtrate, leak-off on embedment Oil and Gas Rates Condensate Multi-Porosity Unconventional Reservoirs 47

48 10000 OIL RATE VS. r P35 (Source of rate data: Martin, Solomon and Hartmann, 1997) (Source of r p35 data: Aguilera, ) q = (r p35 ) R 2 = OIL RATE, B/D Gaspe HTD potential / well 120 BOPD (or gas equivalent) HTD r p to 1.5 μm Vertical Well Published sources Best fit PORE THROAT APERTURE r P35 Servipetrol, Dr. Roberto Aguilera,

49 10000 OIL RATE VS. r P35 (Source of rate data: Martin, Solomon and Hartmann, 1997) (Source of r p35 data: Aguilera, ) q = (r p35 ) R 2 = OIL RATE, B/D Gaspe HTD potential / well 120 BOPD (or gas equivalent) HTD r p to 1.5 μm Published sources Best fit PORE THROAT APERTURE r P35 Servipetrol, Dr. Roberto Aguilera, 2004 JUNEX PRESS RELEASE, Feb 23, 2015: 316 BOPD Non-stimulated horizontal well, Forillon Formation 49

50 PETROPHYSICAL DUAL, TRIPLE AND MULTIPLE POROSITY MODELS DISCUSSED PREVIOUSLY CAN BE LINKED TO OIL AND GAS PRODUCTIVITY 50

51 Linear Flow in a Dual-Porosity Reservoir towards a Hydraulic Fracture of Infinite Conductivity (Adapted from Aguilera, SPE 16442, 1987) 51

52 DECLINE ANALYSIS IN INFINITE-ACTING TRIPLE POROSITY RESERVOIR WITH RESTRICTED INTERPOROSITY FLOW DOMINATED BY LINEAR/BILINEAR FLOW (Leguizamon and Aguilera, SPE , 2011) qd = dimensionless rate, td = dimensionless time, w = storativity ratio, f = function, cc = commingled completion exponent, d = dual, t= triple 52

53 Infinite-Acting Linear Reservoir with Restricted Interporosity Flow

54 Infinite-Acting Reservoir with Unrestricted Interporosity Flow

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66 Tight Gas Field, Well i1 66

67 Triple Porosity q Decline Commingled Completion Production Matching 1.E+06 History Matching Well 1Well 2 Measured Rate Calculated rate 1.E+05 q, m3 / d 1.E+04 1.E+03 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 Time, hours 67

68 Tight Gas Field, Well i1 68

69 Tight Gas Field, Well i3 69

70 Tight Gas Field, Well i3 BDF 70

71 Slide 71 Inter-linear Flow Period Multi-Porosity Unconventional Reservoirs 71

72 Slide 72 1.E+03 1.E+02 1.E+01 1.E+00 Decline Rate with Unrestricted Inter-Linear Transition Flow Triple Porosity Model Dominated by Linear Flow Linear Flow (slope = -0.5) Unrestricted Transition (slope -0.75) qd 1.E-01 1.E-02 1.E-03 Linear Transition 1.E-04 1.E-05 Linear 1.E-06 td Multi-Porosity Unconventional Reservoirs 72

73 Hamm and Struik (2011) 73

74 Slide 74 Slope 0.75 Multi-Porosity Unconventional Reservoirs 74

75 Slide 75 Slope 0.75 Multi-Porosity Unconventional Reservoirs 75

76 Conclusions Multi-porosity models allow integration of petrophysical and production decline analysis and provide input data for material balance (and simulation) studies. There is a continuum between conventional gas, tight gas and shale gas reservoirs (same for oil reservoirs). 76

77 Slide 77 Acknowledgements CNOOC NEXEN GFREE Research Team Schulich School of Engineering at U of C Servipetrol Ltd. Paper # Paper Title Presenter Name Multi-Porosity Unconventional Reservoirs 77

78 Slide 78 Thank You Paper # Paper Title Presenter Name Multi-Porosity Unconventional Reservoirs 78

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